Method for the protection of trees

ABSTRACT

The present invention provides a method for the prevention/treatment of bark beetle and/or wood borer infestation of trees comprising treatment of the tree with a composition comprising a macroyclic lactone.

This application is a continuation of copending U.S. application Ser.No. 11/909,331, filed on Sep. 21, 2007, herein incorporated by referencein its entirety for all purposes

The present invention relates to a method for the prevention/treatmentof bark beetle and/or wood borer infestation of trees comprisingtreatment of the tree with a composition comprising a macroycliclactone. In particular, the present invention relates to the use ofemamectin benzoate in a method for the prevention/treatment of barkbeetle infestation of trees.

A number of species of bark beetle cause a large amount of destructionto trees, in particular pine trees. Of these destructive species, thesouthern pine beetle (Dendroctonus frontalis Zimmerman) mountain pinebeetle (D. ponderosae Hopkins), the western pine beetle (D. brevicomisLeConte), the spruce beetle (D. rufipennis Kirby), the Douglas firbeetle (D. pseudotsugae Hopkins), the pine engraver (Ips pini Say), thepiñyon ips (I. confuses LeConte), the California five-spined ips (I.paraconfusus Lanier) and the Arizonia five-spined ips (I. leconteiSwaine) are of particular note. Secondary bark beetles, including I.avulsus (Eichoff), I. grandicollis (Eichoff) and I. calligraphus(Germar), also are known to cause significant pine tree mortality in thesoutheastern United States. These beetles normally attack trees stressedby drought, lightening strikes, root disturbances, and other factors. Inaddition, wood boring cerambycid beetle larvae may also causesubstantial damage to trees.

The beetles bore into the trees and mated adults dig galleries andchannels under the bark. Eggs deposited in these channels hatch intolarvae which feed on the cambium layer beneath the bark. The channelsthey form cut off the supply of water and nutrients and result in thedeath of the tree. In addition, the beetles may also carry fungi ontheir bodies which can germinate and spread within the trees—such fungimay also change the colour of the wood.

The southern pine beetle (SPB) (D. frontalis Zimmermann), is the mostimportant pest of pine forests in the southern United States. Local andregional outbreaks of SPB cause severe economic losses on a nearlyannual basis. Recently, an unprecedented outbreak extended across muchof the southeast United States. During the period from 1999 to 2002,losses due to SPB-caused tree damage and mortality were estimated atover $1 billion (Report on losses caused by forest insects, SouthernForest Insect Work Conference, 2000, 2001, 2002 and 2003). The SPB doesnot just affect timber industry; it also has a significant impact onrecreation, water, and wildlife resources as well as residentialproperty. The urban/wildland interface is continuing to expand thusplacing more high-valued residential trees at risk to SPB attack. Thecurrent abundance of susceptible trees and forests underlines theimportance of the development of new methods to protect individual treesagainst SPB attack.

Protection of individual trees from SPB and Ips engravers hashistorically involved applications of chemical insecticides to theentire bole of the tree using hydraulic sprayers. Several products hadbeen registered with the Environmental Protection Agency (EPA) for thisuse, including benzene hexachloride (BHC), Lindane®, fenitrothion(Pestroy®) and chlorpyrifos (Dursban®), but recently the use of the lastof these, Dursban®, was withdrawn. In 2003, bifenthrin (Onyx®) wasregistered by EPA for use against several species of bark beetlesincluding SPB and Ips engravers on ornamental plantings, but so far thisproduct has not been made widely available to consumers and is notregistered for use in forest situations. Even when available,insecticide spray applications have limitations. They are expensive,time-consuming, are a high risk for worker exposure and drift, and aredetrimental to natural enemies (Billings 1980).

Systemic insecticides have been suggested as a potentially useful toolfor protection of individual trees or forested areas. One of the firstto be tested, acephate (Orthene®), was applied to foliage at twodifferent rates (Crisp, Richmond, and Shea 1979 unpublished data, inBillings 1980). The treatments were reported to reduce SPB larvalsurvival, but had no effect on eggs, pupae, callow or parent adults. Amore recent study evaluated fenitrothion (Pestroy®) and a combinationtreatment of sodium N-methyldithiocarbamate (SMDC, Vapam®) plus dimethylsulfoxide (DMSO) applied to bark hacks and dicrotophos (Bidrin®) appliedby Mauget Injectors™ (Inject-a-icide-B®) to trees at the leading edge ofSPB infestations (Dalusky et al. 1990).

Although tree mortality was not prevented by any of the treatments,dicrotophos was found to significantly reduce both egg gallery lengthand subsequent brood production. Because dicrotophos has a relativelyhigh mammalian toxicity, it is not available to the general public.Oxdydementon methyl (Metasystox-R) applied by Mauget injectors(Inject-a-cide®) is registered for use against several Dendroctonus andIps species of bark beetles, but is not registered for SPB.

Due to the highly destructive nature of these beetles, new and moreeffective methods and compositions for protecting trees from theirattack are always required.

Emamectin benzoate, an avermectin derivative, has shown systemicactivity in pine and is highly effective against pine wood nematode,Bursaphelenchus xylophilis (Steiner & Buhrer) Nickle (Takai et al. 2000,2001, 2003a, 2003b), and coneworm, Dioryctria spp. (Grosman et al.2002), with protection lasting more than three years. Denim® (emamectinbenzoate) is currently registered for use in foliar spray applicationson colei crops against several lepidopteran species.

It has now been found that emamectin benzoate is surprising effectiveagainst bark beetles and wood borers.

Accordingly, the present invention provides a method for theprevention/treatment of bark beetle and/or wood borer infestation oftrees comprising treatment of the tree with a composition comprising amacroyclic lactone.

A macrocyclic lactone compound is a compound having a ring in itschemical structure made up of twelve or more atoms. The atoms may beselected from carbon, oxygen, nitrogen or sulphur, preferably the atomsare carbon and oxygen. In an embodiment, the ring has up to 20 atoms.Examples include spinosad (737), avermectin and avermectinmonosaccharide derivatives, such as abamectin (1), doramectin(25-cyclohexyl-5-O-demethyl-25-de(1-methylpropyl)avermectin A_(1a); CASRN 117704-25-3), emamectin (291), eprinomectin((4″R)-4″-(acetylamino)-4″-deoxyavermectin B₁; CAS RN 123997-26-2),ivermectin (5-O-demethylayermectin A_(1a) (i) mixture with5-O-demethyl-25-de(1-methylpropyl)-25-(1-methylethyl)avermectin A_(1a)(ii), CAS RN 70288-86-7 (70161-11-4+70209-81-3)) and selamectin((5Z,25S)-25-cyclohexyl-4′-O-de(2,6-dideoxy-3-O-methyl-α-L-arabino-hexopyranosyl)-5-demethoxy-25-de(1-methylpropyl)-22,23-dihydro-5-(hydroxyimino)avermectinA_(1a); CAS RN 165108-07-6), and milbemycin derivatives, such asmilbemectin (557), milbemycin oxime((6R,25R)-5-demethoxy-28-deoxy-6,28-epoxy-25-ethyl-5-(hydroxyimino)milbemycinB mixture with(6R,25R)-5-demethoxy-28-deoxy-6,28-epoxy-5-(hydroxyimino)-25-methylmilbemycinB), moxidectin((6R,23E,25S)-5-O-demethyl-28-deoxy-25-[(1E)-1,3-dimethyl-1-butenyl]-6,28-epoxy-23-(methoxyimino)milbemycinB; CAS RN 113507-06-5), and SI0009 (a milbemycin B mixture of5-O-demethyl-28-deoxy-6,28-epoxy-25-methyl-[3-[[(methoxyimino)phenylacetyl]oxy]-(6R,13R,25R)—(9CI) and5-O-demethyl-28-deoxy-6,28-epoxy-25-ethyl-13-[[(methoxyimino)phenylacetyl]oxy]-(6R,13R,25R)—(9CI); CAS RN171249-10-8 and 171249-05-1).

The natural Avermectins, which can be obtained from Streptomycesavermitilis, are referred to as A1a, A1b, A2a, A2b, B1a, B1b, B2a andB2b. The compounds referred to as “A” and “B” have a methoxy radical andan OH group, respectively, in the 5-position. The “a” series and the “b”series are compounds in which the substituent R₁ (in position 25) is asec-butyl radical and an isopropyl radical, respectively. The number 1in the name of the compounds means that carbon atoms 22 and 23 arelinked by double bonds; the number 2 means that they are linked by asingle bond and that the C atom 23 carries an OH group.

The pesticides, including spinosad, abamectin, milbemectin andemamectin, are described in the e-Pesticide Manual, version 3.0, 13thEdition, Ed. CDC Tomlin, British Crop Protection Council, 2003-04. Thenumber following the compound name is the entry number given in thePesticide Manual.

In one embodiment, the macrocylic lactone is a compound of formula (I):

in which

R1 to R9 represent, independently of each other hydrogen or asubstituent;

m is 0, 1 or 2;

n is 0, 1, 2 or 3; and

the bonds marked with A, B, C, D, E and F indicate, independently ofeach other, that two adjacent carbon atoms are connected by a doublebond, a single bond, a single bond and an epoxide bridge of the formula

or a single bond and a methylene bridge of the formula

including, where applicable, an E/Z isomer, a mixture of E/Z isomers,and/or a tautomer thereof, in each case in free form or in salt form.

The compound of formula (I) may be in the form of tautomers.Accordingly, hereinbefore and hereinafter, where appropriate, thecompound (I) is to be understood to include corresponding tautomers,even if the latter are not specifically mentioned in each case.

The compounds above are capable of forming acid addition salts. Thosesalts are formed, for example, with strong inorganic acids, such asmineral acids, for example perchloric acid, sulphuric acid, nitric acid,nitrous acid, a phosphoric acid or a hydrohalic acid, with strongorganic carboxylic acids, such as unsubstituted or substituted, forexample halo-substituted, C1-C4 alkane carboxylic acids, for exampleacetic acid, saturated or unsaturated dicarboxylic acids, for exampleoxalic, malonic, succinic, maleic, fumaric or phthalic acid,hydroxycarboxylic acids, for example ascorbic, lactic, malic, tartaricor citric acid, or benzoic acid, or with organic sulphonic acids, suchas unsubstituted or substituted, for example halo-substituted, C1-C4alkane- or aryl-sulphonic acids, for example methane- orp-toluene-sulphonic acid.

Furthermore, compounds of formula (I) having at least one acidic groupare capable of forming salts with bases. Suitable salts with bases are,for example, metal salts, such as alkali metal or alkaline earth metalssalts, for example sodium, potassium or magnesium salts, or salts withammonia or an organic amine, such as morpholine, piperidine,pyrrolidine, a mono-, di- or tri-lower alkylamine, for example ethyl-,diethyl-, triethyl-, or dimethyl-propyl-amine, or a mono-, di- ortri-hydroxy-lower alkylamine, for example, mono-, di- ortri-ethanolamine. In addition, corresponding internal salts may also beformed.

In view of the close relationship between the compounds of formula (I)in free form and in the form of their salts, any reference hereinbeforeor hereinafter to the free compounds of formula (I) or to its salt is tobe understood as including also the corresponding salts or the freecompounds of formula (I) where appropriate and expedient. The sameapplies in the case of tautomers of compounds of formula (I) and thesalts thereof.

In a particular embodiment, the invention is concerned with a compoundof the formula (II):

wherein R1 is methyl or ethyl.

This compound is known as 4″-deoxy-4″-N-methylamino avermectin B1a/B1bor emamectin. It is noted that when R1 is a ethyl group, the compound isthe B1a form and when R1 is methyl, the compound is the B1b form.Generally, the compounds are used as a mixture of the two forms, B1a andB1b, since the structural differences are very slight and amount to thedifference between sec-butyl group and an isopropyl group, and the twocompounds have substantially the same chemical reactivity and biologicalactivities. For convenience, the nomenclature B1a/B1b is employed toindicate the individual compounds and the mixture of such compounds. Inparticular, it is preferred that compositions contain 80% or more of theB1a component and 20% or less of the B1b component, more preferably 90%or more of the B1a component and 10% or less of the B1b component.

In particular, the present invention is concerned with the acid additionsalt of the above compound. The acid may be benzoic acid, benzoic acidsubstituted with one, two or three substitutents selected from the groupconsisting of halogen, hydroxyl, carboxyl, C1-C6 alkyl and C1-C6alkoxyl, benzene sulphonic acid, citric acid, phosphoric acid, tartaricacid or maleic acid. The preferred acid addition salts are formed withbenzoic acid, salicyclic acid, gallic acid, benzenesulphonic acid ancitric acid. The most preferred acid addition salt is that formed withbenzoic acid and the compound comprising this salt is known as emamectinbenzoate.

The active ingredient of the present invention may be applied to treesin any of the ways known in the art, e.g. spraying. However, thepreferred method of application is via tree injection techniques and, inparticular, via the Arborjet Tree IV™ microinfusion system (Arborjet,Inc. Woburn, Mass.).

The active ingredient may be formulated ways any one of a number ofknown ways and, in particular, may be formulated for use in treeinjection methods. The active ingredient may be dissolved in a solventto which a surfactant may be added and it can be applied together withfurther carriers, surfactants or other application-promoting adjuvantscustomarily employed in formulation technology.

Suitable solvents are: aromatic hydrocarbons, e.g. xylene mixtures orsubstituted naphthalenes, phthalates, such as dibutyl phthalate ordioctyl phthalate, aliphatic hydrocarbons, such as cyclohexane orparaffins, alcohols and glycols and their ethers and esters, such asethanol, ethylene glycol, ethylene glycol monomethyl or monoethyl ether,ketones, such as cyclohexanone, strongly polar solvents, such asN-methyl-2-pyrrolidone, dimethyl sulphoxide or dimethylformamide, aswell as vegetable oils or epoxidised vegetable oils, such as epoxidisedcoconut oil or soybean oil; or water. For tree injection methods, asolvent having a low viscosity is preferable.

Depending upon the nature of the active ingredient to be formulated,suitable surface-active compounds are non-ionic, cationic and/or anionicsurfactants having good emulsifying, dispersing and wetting properties.The term ‘surfactants’ will also be understood as comprising mixtures ofsurfactants.

The surfactants customarily employed in formulation technology may befound in the following literature:

“McCutcheon's Detergents and Emulsifiers Annual” MC Publishing Corp.,Glen Rock, N.J., 1988.

M. and J. Ash, “Encyclopedia of Surfactants”, Vol. I-III, ChemicalPublishing Co., New York, 1980-1981.

The invention will now be described with reference to the followingexamples:

EXAMPLES

The intent of the study was to evaluate the efficacy of systemicinjections of emamectin benzoate in reducing success of pine bark beetleattacks on loblolly pine and determine the duration of treatmentefficacy. As SPB populations were extremely low in Texas in 2004, Ipsengravers beetles were used as indicator species.

Two 20-year-old, recently thinned loblolly pine plantations wereselected on land owned by Temple-Inland Forest Products Corporationabout 5 km south of Wells (Angelina County), Tex. Trees in oneplantation were injected for use in a bolt study (Example 1). Trees in a0.2 ha section of the second plantation were injected as part of asingle-tree protection study (Example 2). A staging area also was set upin the second plantation where bolts from the first plantation wereexposed to bark beetles and wood borers.

Example 1

Seventy-five loblolly pine trees, Pinus taeda L., 15-20 cm diameter atbreast height (DBH), were selected in March 2004. Each treatment wasinjected into four cardinal points about 0.3 m above the ground on eachof 15 trees in April (16^(th)-23^(rd)) using the new Arborjet Tree IV™microinfusion system (Arborjet, Inc. Woburn, Mass.). The treatmentsincluded:

-   -   1) Emamectin benzoate (Denim®, 1.92% ai, Syngenta Crop        Science)—Denim® was mixed 1:1 with methanol and applied at 18.6        ml solution per inch of tree diameter at breast height (DBH)        (=0.2 g active per inch DBH).    -   2) Check (untreated)

After 1 (May 24), 3 (July 19) and 5 (September) months post-injection, 5trees of each treatment were felled and two 1.5 m long bolts wereremoved from the 3 m and 8 m heights of the bole. The bolts weretransported to a nearby plantation that was recently thinned andcontained fresh slash material. Each bolt was placed about 1 m apart ondiscarded, dry pine bolts to maximize surface area available forcolonization as well as to discourage predation by ground andlitter-inhabiting organisms. To facilitate timely bark beetlecolonization, packets of bark beetle pheromones (racemic ipsdienol +lanerione combination, ipsenol or cis-verbenol; Phero Tech, Inc., Delta,BC, Canada) were attached separately to three 1 m stakes evenly spacedin the study area. Racemic ipsdienol and cis-verbenol were used with thesecond and third series of bolts deployed in July and September,respectively. The packets were removed after 2 weeks when signs ofattacks (boring dust) were observed on most test bolts, signaling thatnaturally-produced pheromones were present.

Signs of beetle attack (boring dust) were visible on several bolts injust a few days after the bolts had been moved to the staging area andthe pheromone baits deployed. Within 2 weeks, several Ips attacks andnumerous cerambycid egg niches were evident on the bark surface of mostbolts.

A clear panel of acetate (10 cm wide by 25 cm long) was attached to thecenter of each bolt after deployment of bolts to monitor arrival of barkbeetles. The top surface of each panel was coated entirely with StikemSpecial® trapping compound (Michel and Pelton, Emeryville, Calif.). Thetraps were left in place for two weeks.

Each series of bolts were retrieved about 3 weeks after deployment,after observing many cerambycid egg niches on the bark surface of mostbolts. There was concern that if cerambycid larvae were allowed todevelop too long, their feeding activity would obscure or obliterate theIps galleries. Thus, each series of bolts were retrieved and storedtemporarily in a TFS seedling cooler (˜45° F.) to slow cerambyciddevelopment until the bolts could be evaluated.

In the laboratory, two 10×50 cm strips (total=1000 cm²) of bark wereremoved from each bolt. Several measurements were made relating toconstruction of nuptial chambers and egg galleries and development ofbrood:

-   -   1) Number of unsuccessful attacks—penetration to phloem, but no        egg galleries.    -   2) Number of successful attacks—construction of nuptial chamber        and at least one egg gallery extending from it.    -   3) Number and lengths of egg galleries with brood galleries        radiating from them.    -   4) Number and lengths of egg galleries without brood galleries.    -   5) Cerambycid activity, estimated by overlaying a 100 cm² grid        over a portion of each bark strip and counting the number of        squares overlapping area where cerambycid larvae had fed.

Treatment efficacy was determined by comparing Ips beetle attacks andegg gallery length and cerambycid feeding on treated and untreatedbolts. The data were transformed by log₁₀(x+1) to satisfy criteria fornormality and homoscedasticity (Zar 1984) and analyzed by GLM and theFishers Protected LSD test using the Statview statistical program.

The number of Ips engraver beetles landing on individual bolts variedconsiderably but did not differ among the treatments for either heightor series (Table 1). In contrast, the total number of attacks (nuptialchambers constructed) by male beetles often differed among thetreatments. The number of attacks was not necessarily reflective of thesuccess of the attack. As expected, in May, untreated bolts were heavilyattacked. For all three series, nearly all nuptial chambers weresuccessfully constructed on untreated bolts—with at least one egggallery radiating from each nuptial chamber. In sharp contrast, onemamectin benzoate-treated bolts evaluated in May, most attacks wereunsuccessful at the 3 m (79%) and 8 m (69%) heights and all (100%)attacks were unsuccessful at both heights in July and September. Itappeared that nearly all attacks were aborted or the beetles died assoon as they penetrated into the phloem region. There were a fewsuccessful Ips attacks on one tree out of five in May, but these attackswere far fewer in number compared to check trees and were restricted tonarrow strips on the bolt. In May, emamectin benzoate sharply reducedthe total number (81% and 96%) and length (94% and 99%) of egg galleriesat 3 m and 8 m, respectively, compared to check trees (Table 2). In Julyand September, emamectin benzoate completely prevented the constructionof egg galleries in all bolts.

In May, cerambycid larvae were found to have fed upon 30% and 34% of thephloem area on untreated bolts taken from 3 m and 8 m, respectively,during the 3 weeks period between tree felling and bolt evaluation(Table 3). In contrast, very little larval feeding or development wasfound on emamectin benzoate-treated bolts. Overall, this treatmentreduced feeding damage by 93% and 100% on bolts from 3 m and 8 m,respectively. Cerambycid larvae fed upon 23-25% and 9-14% of the phloemarea on untreated bolts taken in July and September, respectively (Table3). In contrast, both series of bolts exhibited no larval feeding ordevelopment on emamectin benzoate-treated bolts from 3 m. Nocolonization occurred at 8 m.

Example 2

Loblolly pine, 15-20 cm DBH, were selected in the second plantation inMarch 2004. Each treatment (the same as those used in Example 1) wasinjected into four cardinal points about 0.3 m above the ground on eachof 6 trees in April (16^(th)-23^(rd)) using the Arborjet Tree IV™system. After 5 weeks post-injection (May 28), frills were cut with ahatchet into the sapwood between the injection points near the base ofthe tree. A cellulose sponge was inserted into each cut and loaded with10 ml of a 4:1 mix of sodium N-methyldithiocarbamate (MS) (Woodfume®;Osmose, Inc., Buffalo, N.Y.) plus dimethyl sulfoxide (DMSO) (AldrichChemical) (Roton 1987, Strom et al. 2004). This method reduces resin tonear zero in 1-2 weeks. The intent was to stress the tree and make itsusceptible to attack by bark beetles without killing it.

Although the study area had adequate rainfall to maintain general treehealth, the Vapam/DMSO treatment had the desired effect of stressing thetrees. Resin weeping down the bark surface was the most visible sign ofstress and this occurred on nearly 40% of study trees (F=0.4487; df=4,25; P=0.7723). The treatments did not differ in proportion of trees withthis stress symptom. Five of the six check trees showed signs of barkbeetle attack (pitch tubes and boring dust) 2 weeks after the Vapam/DMSOtreatment was administered. All study trees were evaluated about 4 weeksafter the Vapam/DMSO treatment (=24 days after initial pheromonedeployment).

Pheromone packets containing racemic ipsdienol + lanerione, ipsenol orcis-verbenol were attached (June 7) atop 3 m stakes evenly spaced inbetween and around the study trees to encourage attack by the three Ipsengraver species. However, the initial results of the bolt trialsuggested that encouraging Ips calligraphus (the largest and most commonspecies) attack alone would allow for easier and more accuratemeasurements of beetle attack success. Thus, ipsdienol and cis-verbenolpheromone baits were deployed on all stakes on June 17^(th). The baitswere changed every 4 weeks.

A clear panel of acetate (10 cm wide by 25 cm long) coated with StickemSpecial® was attached 2 m high on standing trees after deployment ofpheromone baits to monitor arrival of bark beetles. The traps were leftin place for two weeks.

Three weeks after pheromone deployment (June 28), each tree wasevaluated by marking a 30 cm section of bole at a height of 3 m. Allvisible Ips attacks and cerambycid egg niches were counted within themarked area. The number of trees with fading crowns also was recorded.Thereafter, the trees were evaluated weekly for crown fading. Whenmortality did occur, the trees were felled and two bolts taken andevaluated for attack success and gallery length as described inExample 1. All remaining trees were felled 66 days (Aug. 9) afterinitial pheromone deployment when no additional trees had died for 3weeks. Treatment efficacy was determined by comparing tree survival,beetle attacks and egg gallery length on treated and untreated bolts. Asbefore, data were transformed and analyzed by GLM and the Fisher'sProtected LSD test using the Statview statistical program.

All checks were heavily attacked by Ips and most had two or morecerambycid egg niches at 3 m (Table 4). In contrast, emamectinbenzoate-treated trees had significantly fewer Ips attacks at the sameheight. Of the few Ips attacks that were found on these trees, nearlyall appeared to have been unsuccessful based on the fact that the pitchtubes at the entrance holes were dry and brittle. None of the emamectinbenzoate-treated trees had fading crowns (yellowing needles) (Table 6);whereas, two check trees exhibited fading crowns.

The study was discontinued after 66 days when no additional trees hadfaded in 20 days (Table 5). In the end, 5 of 6 (83%) of the check treeshad died due to bark beetle attack. In contrast, all emamectinbenzoate-treated trees survived. Evaluation of cut bolts showed that alltrees had been attacked, but the emamectin benzoate-treated bolts hadsignificantly fewer attacks at both heights than the check (Table 6).All attacks that did occur were completely unsuccessful. Emamectinbenzoate-treated bolts had significantly fewer and shorter Ips egggalleries with and without brood and less area fed upon by cerambycidlarvae compared to the check (Table 7).

In both examples, emamectin benzoate was highly effective in preventingsuccessful attacks by Ips bark beetles and cerambycids one, three andfive months after injection. On the bolts, at least, those male Ips thatinitiated attacks were either deterred or killed upon penetration intothe phloem layer and exposure to the active ingredient. It is surmisedthat any pheromone production by males as they burrow through the barkwas halted prematurely. Without these pheromones, very few, if any,females were attracted to the host material or entered the nuptialchamber to mate and begin construction of egg galleries. Even whenfemales did arrive on a few of the logs of the first series and beganconstruction of galleries, the galleries were very short and brood didnot developed beyond the initial larval instars. Assuming that thisscenario also occurred in the standing trees, the halting of pheromoneproduction upon male contact with the phloem layer also halted theattraction of additional males, thus preventing the mass attack of thehost tree.

The emamectin benzoate dose (0.2 g ai/inch of tree diameter) used in2004 has been found to prevent successful attack by Ips engravers. If alower dose were to be injected in trees at the leading edge of an activeSPB infestations, the injected trees may serve as trap trees, i.e. allowsuccessful mass attack, gallery construction and egg laying by adultSPB, but the larvae would not develop and no brood adults would beproduced. If the treatment proved successful, it is conceivable thatlocal populations of SPB would decline and the progression of theinfestation would stop.

REFERENCES

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TABLE 1 Attraction to and attack success and gallery construction of Ipsengravers beetles on loblolly pine bolts cut one, three and five monthsafter trunk injection with emamectin benzoate Mean # of Nuptial Mean #of Chambers Nuptial Without Chambers Mean Mean # of Egg with Egg Total #of Evaluation Bolt Ips Galleries Galleries Nuptial period Height Trt*caught/Trap No. Total No. Total Chambers 1 Month 3 m Emamectin 3.8 a14.6 c  78.5 4.0 a 21.5 18.6 a  Post- Check 6.8 a 0.0 a 0.0 16.0 b 100.0 16.0 a  Injection 8 m Emamectin 4.8 a 9.0 c 69.2 4.0 a 30.8 13.0ab (May) Check 5.0 a 0.2 a 0.7 27.2 b  99.3 27.4 c  3 Months 3 mEmamectin 1.8 a 11.0 b  100.0 0.0 a 0.0 11.0 ab Post- Check 2.4 a 0.8 a13.3 5.2 c 86.7 6.0 a Injection 8 m Emamectin 3.4 a 8.4 c 100.0 0.0 a0.0 8.4 b (July) Check 2.8 a 0.0 a 0.0 3.8 b 100.0 3.8 a 5 Months 3 mEmamectin 1.2 a 3.8 b 100.0 0.0 a 0.0 3.8 a Post- Check 1.6 a 0.0 a 0.05.2 b 100.0  5.2 ab Injection 8 m Emamectin 0.4 a 4.4 b 100.0 0.0 a 0.04.4 a (September) Check 2.2 b 0.0 a 0.0 7.8 b 100.0 7.8 a *Meansfollowed by the same letter in each column are not significantlydifferent at the 5% level based on Fisher's Protected LSD

TABLE 2 Mean number and length of egg galleries constructed by Ipsengravers beetles in loblolly pine bolts cut one, three and five monthsafter trunk injection with emamectin benzoate Number of Egg GalleriesLength of Egg Galleries Without With Without With Brood Brood BroodBrood Evaluation Bolt % % Total % % Total Period Ht Trt* No. Total No.Total Galleries cm Total cm Total Length 1 Month 3 m Emamectin 10.0 a 80.6 2.4 a 19.4 12.4 a 15.5 a  50.5  15.2 a 49.5  30.7 a Post- Check29.0 b  44.1 36.8 c  55.9 65.8 b 114.8 b  23.8 368.4 c 76.2 483.2 cInjection 8 m Emamectin 4.0 a 95.2 0.2 a 4.8  4.2 a 12.3 a  91.1  1.2 a8.9  13.5 a (May) Check 30.0 b  31.7 64.6 d  68.3 94.6 b 104.4 b  17.7483.8 c 82.3 588.2 b 3 Months 3 m Emamectin 0.0 a 0.0 a  0.0 a 0.0 a 0.0 a  0.0 a Post- Check  2.2 ab 12.9 14.8 b  87.1 17.0 c 14.4 b  9.2142.0 b 90.8 156.4 c Injection 8 m Emamectin 0.0 a 0.0 a  0.0 a 0.0 a 0.0 a  0.0 a (July) Check  1.0 ab 7.7 12.0 bc 92.3 13.0 c  2.4 ab 1.5153.6 c 98.5 156.0 c 5 Months 3 m Emamectin 0.0 a 0.0 a  0.0 a 0.0 a 0.0 a  0.0 a Post- Check 2.8 c 17.7 13.0 b  82.3 15.8 c 9.8 c 6.1 150.6b 93.9 160.4 c Injection 8 m Emamectin 0.0 a 0.0 a  0.0 a 0.0 a  0.0 a 0.0 a (September) Check  2.4 bc 11.9 17.8 b  88.1 20.2 c 10.8 b  4.6223.4 b 95.4 234.2 c

TABLE 3 Cerambycid larval feeding in loblolly pine bolts cut one, threeand five months after trunk injection with emamectin benzoate PercentPhloem Area Consumed by Larvae 1 Month Post 3 Months Post 5 Months PostBolt Injection Injection Injection Height Trt* (May) (July) (September)3 m Emamectin  2.2 a 0.0 a 0.0 a Check 29.9 c 23.0 bc 9.3 c 8 mEmamectin  0.0 a 0.0 a 0.0 a Check 34.1 c 24.5 b  14.2 b  *Meansfollowed by the same letter in each column are not significantlydifferent at the 5% level based on Fisher's Protected LSD

TABLE 4 Attraction and attacks by Ips engravers beetles and cerambycidsto standing loblolly pine after trunk injection with emamectininsecticides Mean # of Attacks/0.3 Bole Section at 3 m Mean # of Ipsafter 24 days Treatment Caught/Trap Ips Cerambycid Emamectin 1.2 a  0.5a 0.8 a Check 6.5 b 14.7 c 4.3 a *Means followed by the same letter ineach column are not significantly different at the 5% level based onFisher's Protected LSD.

TABLE 5 Visible signs of mortality on standing loblolly pine after trunkinjection with emamectin benzoate Percentage of Trees With Fading CrownsAfter: Treatment 24 days 32 days 39 days 46 days 52 days 66 daysEmamectin 0.0 a  0.0 a  0.0 a  0.0 a  0.0 a  0.0 a Check 33.3 ab 66.7 b83.3 b 83.3 b 83.3 b 83.3 b * Means followed by the same letter in eachcolumn are not significantly different at the 5% level based on Fisher'sProtected LSD

TABLE 6 Effects of emamectin benzoate insecticides on attack success andgallery construction of Ips engraver beetles on loblolly pine bolts cutafter tree mortality or the end of the trial Mean # of Nuptial Mean # ofChambers Nuptial Without Chambers Mean Egg With Egg Total GalleriesGalleries # of Bolt % of % of Nuptial Height Treatment No. Total No.Total Chambers 3 m Emamectin 3.0 ab 100.0 0.0 a 0.0 3.0 a Check 3.2 ab32.8 6.5 b 67.2  9.7 bc 8 m Emamectin 1.3 ab 100.0 0.0 a 0.0 1.3 a Check0.8 ab 12.2  6.0 bc 87.8 6.8 b * Means followed by the same letter ineach column are not significantly different at the 5% level based onFisher's Protected LSD.

TABLE 7 Effects of emamectin on gallery construction of Ips engraversbeetles and cerambycid larval development in loblolly pine bolts cutafter tree mortality or at the end of the trial. Mean # of Egg GalleriesMean Length of Egg Galleries Without With Without With Brood Brood BroodBrood Cerambycid % of % of Total % of % of Total Feeding Bolt Ht Trt*No. Total No. Total Number cm Total cm Total Length Area 3 m Emamectin 0.0 a  0.0 a  0.0 a 0.0 a  0.0 a 0.0 a 0.0 a Check 17.2 b 59.5 11.7 b40.5 28.8 b 108.3 b  48.0 117.2 b 52.0 225.5 b  3.6 b 8 m Emamectin  0.0a  0.0 a  0.0 a 0.0 a  0.0 a 0.0 a 0.0 a Check 18.5 c 40.5 27.2 b 59.545.7 b 91.0 b  30.8 204.0 c 69.2 295 b   6.2 bc *Means followed by thesame letter in each column are not significantly different at the 5%level based on Fisher's Protected LSD.

The invention claimed is:
 1. A method for the reduction of bark beetlelarvae feeding or development in the phloem area of trees comprisingtreatment of the tree with a composition comprising a macrcoycliclactone selected from abamectin and emamectin benzoate, wherein thecomposition is applied to the tree using an injection technique, andwherein the tree includes at least one bark beetle.
 2. The methodaccording to claim 1, wherein the macrocyclic lactone is abamectin. 3.The method according to claim 1, wherein the macrocyclic lactone isemamectin benzoate.